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Problem with UART?

alexus2013
Prodigy 50 points

Hey!

I wanted to connect to UART to see what boot messages im getting but so far i'm having issued with output. Im pretty much getting gibberish,
I would assume that is due to baud rate but i set it exactly to what documentation says 115200, 8 bit, none, 1, no handshake

I have pin out like this:
Tip -  TX
Rig -  RX
Rig2 - GND

I tried all boud rates and different tx, rx positions but no luck so far.

I used PL2303HX UBS-Serial TTL cable.

Can some one help me out?

Tnx

  • 0
    TI__Genius 9935 points

    Alexus,

    The serial settings are indeed 115200,8,No,1, no hs.

    Did the driver for the PL2303HX USB-Serial cable install correctly? What terminal program are you using? I use Tera Term 4.77 http://en.sourceforge.jp/projects/ttssh2/releases/

    Check your signals against the LightCrafter System Board schematic:  http://www.ti.com/lit/ml/dlpr003/dlpr003.pdf page 3.

  • 0 in reply to Pascal DLP
    Prodigy 50 points

    Thank you for reply

    i use TeraTerm too!
    Connection seam same as indicated on the diagram, driver look like installed correctly :(
    I don't even know what might cause and issue

  • 0 in reply to alexus2013
    TI__Genius 9935 points

    Alexus,

    If you are seeing "garbage" rather than text, you may have a damaged cable or connector. I verified that if you select the wrong serial port, you will see nothing on the console. However, if you have an electrically bad connection, and you are connected to the correct serial port, you may see "garbage" instead of the text, even if the terminal parameters are set correctly.

    Have you been able to use your serial cable to communicate with other devices?

  • 0
    Intellectual 340 points

    Hi!

    I am also facing problems with the UART connection. On the terminal emulator I receive only garbage, which I assume is due to a wrong decoding setting. However, I have until now not been able to get this working. I am using the FTDI TTL-232R-3V3-WE with black on outermost, yellow on the ring and orange on the tip. This should correspond to the circuit plan. I have also tried interchanging tx/rx. However, with my current configuration I receive a very plausible stream of about 1300 characters in the boot sequence, and a few characters when changing modes. Unfortunately it is all garbage. 

    To find the error I have tried various terminal settings without success. I have also had the cable on a Mac (FTDI driver, ZTerm, goSerial), Windows (FTDI driver, Tera Term) and Linux (libUSB, moserial). 

    Has anyone experience with this cable? Am I missing a crucial point in the coding settings? 

  • 0 in reply to Jakob Wilm
    Intellectual 340 points

    OK, I realize now that this is the wrong cable. I would need a USB to RS-232. Can you that Digikey part 768-1077-ND is suitable?

    Best regards, 

    Jakob

  • 0 in reply to Jakob Wilm
    TI__Genius 9935 points

    Jakob,

    I don't have any direct experience with the part you reference. However, I looked at the Digikey link, and the cable uses FTDI USB chip. That chip has worked in other adapters, so it should be ok. Can't promise, but would say it is a good chance.

  • 0 in reply to Jakob Wilm
    TI__Expert 6995 points

    Jacob,

    If you are using TTL-232R-3V3-AJ cable note that the signals use a backward convention. LightCrafter needs the tip as receive and middle ring as transmit.

    The LightCrafter board has population option on in-line zero ohm resistors to flip these pins in case the convention changed. Out of the factory, tip is connected to RX of DM365 and middle is connected to TX of DM365.

    I have also seen garbage data when the FTDI driver does not match the FTDI chip in the cable.

    Best regards,

      Pedro

     

  • 0 in reply to PedroGelabert
    Intellectual 340 points

    Hi Pedro,

    thank you for the information. I believe the problem with most any TTL* cable is that it operates at TTL levels, not RS232. TTL is suited for uC programming, etc, while RS232 is what comes out of your grandma's serial port. Correct me if I'm wrong.

    https://www.sparkfun.com/tutorials/215

    I now bought the aforementioned USB-RS232-WE-1800-BT_3.3 and it works like a charm.

    /Jakob